PROJECT SUMMARY/ABSTRACT As melanoma mostly expresses tumor-specific neo-antigens (Ags), immunotherapy such as adoptive cell transfer-based therapy (ACT) is considered a promising treatment option for this notoriously deadly disease. Nevertheless, due to various factors that may weaken therapeutic immunity, the clinical outcomes and benefits of this remedy remain less satisfactory. Importantly, accumulating evidence suggests that the metabolic status of both immune cells and tumor cells has a significant impact on the potency of ACT, and that metabolic reprogramming may represent a viable target for reinforcing immunotherapy. Nucleus accumbens-associated protein-1 (NAC1) is a transcription co-regulator belonging to the BTB/POZ gene family, and is highly expressed in several types of cancer including melanoma. Published studies including our own have shown that NAC1 not only bestows oncogenic potential but also undermines therapeutic outcomes through its transcription- dependent or -independent functions. More recently, we discovered that NAC1 can promote glycolysis through its interaction with HIF-1a, and is critically required for development, survival and function of T cells as well as tumor cells. We also found that NAC1 negatively affects the tumoral expression of major histocompatibility complexes (MHCs); the alteration of NAC1 gene expression occurs during differentiation of the pluripotent stem cell (PSC)-derived T cells, and this alteration is accompanied by changes in the expressions of a number of other genes. Based on these intriguing findings, we hypothesize that NAC1-mediated metabolic reprogramming suppresses anti-tumor immunity; targeting NAC1 would hasten death or reduce resilience of both tumor and suppressor immune cells and modulate the expression of tumor Ags, checkpoint molecules and the related proteins, thereby relieving immune-suppression and reinforcing the efficacy of ACT against melanoma. To test these hypotheses, the current multiple PI application proposes the following highly interactive specific aims: (1) To determine the novel role of NAC1 in T cells; (2) To determine the role of tumoral NAC1 in melanoma immune escape; and (3) To determine the impact of targeting NAC1 in ACT against melanoma. This multiple PI project combines the Yang laboratory?s strength in cancer biology with the Song laboratory?s expertise in tumor immunology. We have already established the mouse and human PSC- derived antigen-specific CD8+ T lymphocytes, and the murine syngeneic and humanized (NOD-scid IL2rgnull) mouse melanoma models for the proposed studies, and are well poised to accomplish the above aims. Completion of this project will not only uncover NAC1 as a unique molecular determinant of tumor-specific immune responses and shed new light on the importance of NAC1 in cancer pathobiology, but also provide novel therapeutic opportunities to enhance ACT against melanoma through the NAC1-targeted strategy.